Halley's comet, an old acquaintance

More than 2000 years, particularly in the year 239 BC, the astronomers spotted a comet in the sky, which would periodically observe every 76 years. It was the that ultimately would be the comet's best-known sky: Comet Halley.

It is named for Edmund Halley, who was the astronomer who first calculated its orbit. Thanks to its calculations and descriptions of previous sightings, said that in 1757 the comet had been seen in the year 1472, 1531, 1607 and 1682 would pass near Earth. Edmund Halley never could see that would be true, because died 16 years ago and only made a mistake in his calculations in a year.

The last time we visited Halley's comet was in 1986, and will not pass close to us again until 2061, when it has completed a new round of its orbit, which extends from 0.6 AU (between Mercury and Venus ) and away until 35 AU, slightly less than the distance to the dwarf planet Pluto.

Halley's comet has its quirks. In our solar system there are two kinds of comets, short cycle and long cycle. The first comes from the Kuiper Belt, an area between 30 and 50 AU from the already discussed in espaciociencia, and second, the Oort cloud, located more than 50,000 AU. Halley's Comet can be assumed to belong to both groups, as the calculations of its orbit shows that originally came from the Oort cloud, but was caught by the gas giant of the Solar System and comet became a short cycle.

To mark the passage of the comet near Earth in 1986, the European Space Agency (ESA) launched the Giotto mission, originally designed by NASA, but declined due to economic cutbacks. The Giotto spacecraft approached only 596 miles of Comet Halley.